ABSTRACT While observational research suggests an association between obesity-related social environment factors with obesity and cardiometabolic risk factors, very little research has addressed the specific factors and pathways linking the social environment to cardiometabolic risk. The primary reasons for this lack of research are: 1) lack of high quality data on diet, activity, measured height and weight over time linked to cardiometabolic risk biomarkers; 2) lack of fine-grain longitudinal data on the introduction, renovation, and closure of food- and activity-related environmental features; and 3) lack of complex statistical models examining each piece of the time-dependent, complex system, accounting for the process by which food, activity, and transportation facilities are established and expanded and the potential for individuals to selectively migrate to locate near such facilities. The 25-year, longitudinal Coronary Artery Risk Development in Young Adults (CARDIA) study provides a wide age range, high quality longitudinal, biological, behavioral and anthropometry and biomarker data of CARDIA, geographic diversity, and different patterns and pace of change across the four baseline cities: Birmingham, Chicago, Minneapolis and Oakland. The research team has developed a unique method to use retrospective and contemporary sources to create data on the timing and placement of introductions, renovations, and closures of: 1) food resources (e.g., restaurants, food shopping); 2) recreation facilities (e.g., trails, parks); and 3) transportation infrastructure (e.g., light rail, bike parking, bike paths) in Birmingham, Chicago, Minneapolis, and Oakland over a 25-year period. Furthermore, we have developed sophisticated statistical models that account for purposeful (as opposed to random) placement of relevant resources in the social environment as well as individuals' ability to selectively migrate to locate near such resources. Study objectives include: 1) Develop and validate new fine-grain measures to capture introductions, renovations, and closures representing changes in: a) parks, trails, and other recreational sites; b) food environments; and c) transportation infrastructure that will be contemporaneously linked to CARDIA respondents' geographic locations over 25 years; and 2) Using this unique data source, estimate the effects of introductions, renovations, and closures of key food and activity facilities and transportation infrastructure on diet and activity behaviors, body weight and cardiometabolic risk in the four field cities over 25 years, while accounting for the endogenous placement of food and activity facilities and selective migration. We will specifically focus on comparisons across individual-level race, income, and education groups to examine how environmental factors contribute to race and SES inequalities in diet, obesity, and cardiometabolic risk from young- to mid-adulthood. The proposed research will improve current understanding of the mechanisms through which social environments (specifically broader societal, economic, and environmental contexts) influence health outcomes.